Alternating-current generator.



P-ATENTED MAR. 27, 1906.

0. P. STEINMETZ.

ALTERNATING CURRENT GENERATOR.

APPLICATION FILED JULY 25. 1904.

Witnesses- Inventor:

Charles F3 Steinmetz.

pounding of a" polyphase'machine can at the several phases.

State of New Current Generators, of which the following is loads and power "the field of a n alternsiting-current the load increases the field flux increases, and the potential at the generator-termmals may current remains practically constant, and

the armature of the ordinary direct-current .mach1ne. v

commutator*polyphase currents are supnnrrnnsrarns CHARLES SlElNA IETZ, or scnnnnoranr, NEW

T FFIGEE' Yoax, Assien'oR to ALTERNATING-OURRENT GENERATOR.

Specification of Letters Patent.

Patented March. arfieoe.

Application filed July 25,1904. Serial No- 217,997

To all tell/0712, may concern: 1 I Be'it known. that I, CHAR ES P. STEIX- METZ, a citizen of the United States, resid- E in'g at Schenectady, county of Sciienectady, York, have invented certain new and useful Improvemen ts in Alternating a specification. o

My invention relates to the cornpound'ng or" alternating-current generators for varyi g factors. 'It ha-sheen proposed heretofore toexcite generator with a constant directcurrent excitation supplemented by a second excitatioz'i, corresponding to the series excitation of a com pound-wound direct-current generator, ob tained by rectifying the whole or a part of the armature-current and delivering it to aseparate winding on the field. This method of compounding corresponds strictly to that employed in direct-current generators. As

be. maintained constant or increased. It does not compensate, however,.for'the variation in armature reaction due to varying powerfactor. The magnetizing effect of the armature-currenton the field varies greatly with the power factor, even if-the amount of consequently the method ofcompounding which I have briefly described is not suitable for usewith a generator supplying a load. of widely-varying power factorf Furthermore,'with the above arrangement the comest be adjusted on y for the average load of i Consequently, if the, phases are loaded unequally the voltage of the phasehaving the heaviest load or the lowest power factor will be too low and-the volrent generators that has been suggested heretofore-consists in supplying the field with a distributed winding and a commutator like Through brushes bearing on this plied to the distributed wii'iding, thttsecurrentsbeing so derived from the armaturecur'rentsthat proper compounding is obarmature field may for and the different series winding-of an ordinary direct-current machine. This arrangement, while it accurately compensates for varying load and power factor and while it compounds the phases separately, since each portisn of the have adjacent to it a distributed winding, carrying a current proportional in amount and varyingfin power factor therewith, is subject to the i; sadyantags that since it is self-exciting it may lose its excitation in case of a short-circuit,.and, moreover, the excitation furnished by the shunt-transformers is not necessarily oonstant but depends upon the voltage atthe armature-terminals.

The object of my inventionis to provide a novel arrangement for compounding, Wl'llCh combines the advantages of both the arrangementsbriefly described above. In common with the second arrangement, varying; loads and power factors are properly compensated phases of the armature are separately compounded, while it possesses the advantages of the first arrangement, in

that no danger exists of its losing its excita-,

tion under any circumstances.

My invention consists in employing a distributed field-winding with a comnmtator,

such as has been heretofore mentioned, and supplying to 'fixedpoints. thereon a direct current excitation. and accomplishing the compounding by means of a series transformer connected to brushes bearing on the commutator.

My invention will best be understood by reference to the accompanying drawings, in which a i p F igure 1. shows a single-phase alternatingcurrent gei'ierat-or arranged in accordance with my invention, and Fig. 2 shows apolyphase generator similarly. arranged teferring first to Fig} 1, A represents the armature of an alternatirig-current generator connected to the mains a a. l represents the field-winding, which isshown as a "dis,- tributed winding connected to aniany-ymrt commutaton Although both armature and field windings are shown as tirammc-ring windings, it will he understood that the all matureavimling may he of any well-known type of distributed winding supported in holes or slots in a laminated structure, while the tield-windingmay he similar to an) of the \\'ell*l(th i\\n forms of armatitre-windings for direct-current machines.- In addition to its connections to the commutator C the fieldwinding 1 is connected at two fixed points to the collector-rings c. E re )resents a directcurren't exciterwvhich supplies the field-winding 1" through the collector-rings. 'lhe direct current in the field-winding'F produces a constant lield, rotating with the field structure in the same manner as when a polar winding is employed. In addition to the di- .rect-current excitation an alternating current is supplied from the series transformer T through the commutator-brushes b b to the field winding F. This current being obtained ,t'rom a series transformer varies both in magnitude and in phase with the armature-current .'and since the brushes b b are fixed in'space and are positioned o posite to the armatitre-terminals each turn oi the fieldwinding F carries at all times a current which varies in magnitude and phase with the current in an adjacent turn of the. armaturewinding. The armature reaction mav thus he neutralized for all loads and power factors and proper compounding thereby secured.

In Fig. '2 Ihave shown my invention as applied to athree-phase machine. The armature-field A is connected to the three linewires (1, a and (1 The field-windi gs E is provided with a commutator C and collectorrings c, the latter being supplied with directcurrent from the exciter E. Instead of two commutator-brushes three brushes b, If, and

' b are employed, and three transformers T,

T, and 'l are connected to the brushes, the primaries of the transformers being connected in circuit with the several phases of the armature. With the connections as shown it will be seen that if the load on one phase-- as, for instance, on the mains a (KL-IS greater than that on the other two phases the potential impressed upon brushes 1; and b will be greater than the potential impressed between brushes and if or I! and b". A larger cu rrcnt conse uently flows in that partol' the field-winding which is adjacent to the most ltea\'ll loaded part of the armature-' Thus the ddl'c-rent loads on the winding.

separate phases are separately and automat- 1 callv compensated l'or. 'hat is true as to the amount of current-[low is also true as to ihase.

ol' the loads on the ot hcr phases, the phase of the current in the adjacent portion ol the field-winding will also differ from the phase of the currents in the rest ol the field-winding.

lithe power l'actor ol' the load on one phase s dill'ercnt from the power lactor A number of alternators compounded in accordance with my invention ma be operated in parallel, the same as with compounded direct-current generators. In Fig. 2 I

have shown equalizer connections t from the terminals of the three compounding transformers, these connections corresponding to the equalizer connect-ions employed withthe series wind ng of a direct-current generator. While for the sake of simplicity I have illustrated myinvention as applied to a bipolar machine, it will of course be understood that my invention is applicable to alternating-current generators of any number of poles, as well as, of any number of phases.

Many modifications may be made in the arrangement and connections shown without departing from the spirit of my invention, and I aim in the appended claims to cover all such modifications.

What I claim as new, and desire to secure by Letters Patent of the United States, is 1. In an alterating-current generator, a field structureprovided with a distributed Winding and a many-part commutator connected thereto, brushes bearing on said contmutator, means for supplying direct current to the field to magnetize the field structure on a line fixed relatively thereto, and means for supplying to said brushes a current varying in magnitude and phase with the armature-c urrent 2. In an alternating-current generator, a field structure provided with a distributed winding and a many-part cummutator connected thereto, brushes bearing on said commutator, means for supplying direct current to the field tomagnetize the field structure on a line fixed relatively thereto, and a series transformer having its secondary connect-ed to said brushes and its primary connected in the armature-circuit.

3. In an alternating-current generator, a distributed field-winding provided with. amany-part commutator, brushes bearing on said commutator, means fo supplying to said brushes current varying in magnitude and phase with-the armature-current, and means for so )plying directcurrentto fixed poi ts on said field-winding.

4. In an alternating-current generator, a distributed lield-winding provided with a litany-part commutator, brushes bearing on said commutator, a'series transformer having its primary in the arnatture-circuitand its secondary connected to said brushes, and

; means for supplying direct current to fixed points on said field-winding.

In an alternating-current generator, a distributed field-winding provided with a many-part commutator and with collectorrings, commutator-brushes, collector-ring brushes, a source of dircc-t current connected to-t he latter hriniiig and a erie I ransl' rnn-r having its secondary connected to the com mutator-brushes and its primary conneeted in the armature-circuit.

6. In an alternating-current generator, a distributed field-winding, means for supplying tofsaid winding at points fixed in space a current varying in magnitude and phase with the armature-current, and means for supply-- ing direct current to said winding at points revolving therewith. I

7. In an alternating-current genera-tor, a distributed field-winding, means for supplying to said winding at points fixed with re' spect to the armature-terminals and opposite thereto a current varying in magnitude and phase with the armature-current, and means for supplying direct current to said winding *at points fixed with respect to said winding.

- 8. In a polyphase generator, a distributed field win'ding, means for supplying to the portion ofisaid Winding at any given instant adjacent to a phase 10fthe armature-winding a current varying in magnitude and phase 4 the current in said phase of the arma- 5 ture, and means for supplying "a direct ourrent to fixed points on said field-winding;

9.1 In a polyphase generator, a distributed field-winding,' means for supplying to said winding at points fixed with respect to the terminals of the several phases of the arma- V ture and opposite thereto currents varying in v magnitude and phase with the current in the phase of the armature opposite thereto, and

means for supplying direct current to fixed points on said winding;

10. In a polyphase generator, a distributed field-winding provided with a many-part commutator, brushes bearing on said commutator, series transformers having their primaries connected in circuit with the several phases of the armature and their second- Winding provided with a many-part commutator and with collector-rings, a plurality of brushes bearing on said commutator and corresponding in position to the terminals of the several phases of the armature, series trans formers having their primaries connected in circuit with the several phases of the primary and their secondaries connected to the commutator-brushes, and a source of direct curv rent connected to said collector-rings.

In witness whereof I have hereunto set my hand this 22d day of July, 1-904.

' CHARLES STEINMETZ. Witnesses:

BENJAMIN B. HULL,- HELEN ORFORD. 

